Fume evacuation hood



United States Patent 3,451,326 FUME EVACUATION HOOD Jacques Valensi, 1 Rue Honnorat, Marseille, France Filed May 9, 1967, Ser. No. 637,120 Claims priority, application France, May 26, 1966,

rm. (:1. F233 11/00 US. Cl. 98-415 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to devices for the evacuation of fumes, vapors or foul air inside enclosures, like residential rooms, laboratories, foundries, etc., and it relates particularly to improvements to hoods used generally to facilitate the guiding of fumes, vapors, etc., toward an evacuation duct under natural or forced draft.

The primary objective of this invention is to design such hoods so that they respond better than prior art structures to the various practical requirements, particularly insofar as their efficiency and suppression of harmful effects are concerned which result from the undesired backfiow of the fumes into the area to be purified.

It is known that vent hoods according to the prior art, such as those placed for example on top of laboratory stands, kitchen ranges, etc., sometimes take up a relatively large volume, caused by their generally wide aperature on their inner portion. The result is that the fumes or vapors often are driven back and spread into the room which is supposedly being purified. Furthermore, the vertical distance between the original source and the hood is relatively large, so the hot fumes or gases entrain a considerable amount of cold air as they rise due to natural convection. The effect of such movement of air is to cool these fumes or these gases, and to increase their volume and density. This contributes towards pushing the undesired fumes back into the room.

It is to be noted furthermore that with the systems known in the prior art the vapor has a tendency of being directed toward the cold walls of the room or area and to be deposited on the glass windows of the room instead of being evacuated by the fume conduit.

This invention precisely relates to improvements in vent hoods which make it possible to obviate the inconveniences enumerated above.

Substantially, these improvements consist in providing inside the hood, in the vicinity of its lower section a covering in the shape of a frusto-pyramid whose large base bears down on the walls of the hood, while its other base, located at a higher level, is provided with a cylindrical or tapered conduit extending toward the bottom of the hood on its outside. Orifices are provided on the walls of the frusto-pyramid, preferably in the vicinity of the wall of the hood.

The invention will be better understood from the following detailed description thereof taken in conjunction with the accompanying drawings in which:

FIGURE 1 of this drawing is a vertical section of a chimney hood or vent system equipped with the improvements according to the invention; and

FIGURE 2 is a plan view of a covering for a chimney which is equipped with the improvements according to the invention.

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FIGURE 1 shows an embodiment of the improvements according to the invention, applied to a chimney hood or vent system located in the kitchen of a residential dwelling, wherein there is shown the kitchen wall 1 and an operating plan 2. The equipment is located at a level which is likely to generate harmful fumes, such as the fumes or vapors originating from a hot plate, for example. A hood 3 is provided above the operating plan or level 2. This hood has a parallelepipedal shape of square cross section in the embodiment shown.

According to the invention a covering is provided in the lower portion of this hood, comprising particularly a frusto-pyramidal element 4, whose edges bear down on the walls of the hood. FIGURE 2 is a top view of this truncated pyramid 4, which is regular and has substantially square bases. It can be seen that the walls of the pyramid are provided with legs 5, 6, 7, 8, allowing it to be suitably attached to the hood 3. It can also be seen that the walls of the pyramid in the vicinity of its large base are provided with rectangular grooves 9, 10, 11, 12 located substantially in the center of each side. The part played by these grooves will be explained below in more detail.

The upper part of the pyramid 4 is extended downward by a parallelepipedal conduit 13, located in the axis of the pyramid. Said conduit could possibly have the shape of a revolution cylinder or a cone. The length of this conduit is so selected that the lower orifice is in the vicinity of the emission surface of the gases to be evacuated, but nevertheless at a sufficient distance to avoid harming the operators and the operation of the equipment and utensils placed on the working surface level 2. The straight section of this conduit will be determined as a function of the volume of the gas to be evacuated so that the speed of such gases at the entrance of the conduit will be higher than the speed of the convection currents above the working surface.

FIGURE 1 shows that the hood wall 3 is extended downward to a flange 14 having at its lower end a ridge 15, whose function will be explained below. Finally, it can be seen that the top of the hood is provided with a suction mechanism 16 connected to an evacuation conduit 17. It should be noted that this mechanism 16 is not indispensable and the hood as described also could operate very well by natural draft.

The device just described is to improve the draft of the chimney or vent system and to avoid any backfiow.

Fumes which accidently would be pushed back from the hood while being evacuated via conduit 13 are then evacuated via the orifices 9, 10, 11, 12, located on the walls of the pyramid. In fact due to the suction across orifices 9, 10, 11, 12 a substantially horizontal whirlwind is produced in the vicinity of these zones outside the hood, forming a trap for the fumes which have been pushed back accidentally. It may be noted in this connection that the front side of the hood has been extended by a flange 14, in order to favor the formation of the whirlwind. This flange simultaneously bears down :along the vertical edge 18 of the adjacent wall of the pyramid at the outer side of the hood.

It should be noted on the other hand that the presence of conduit 13 favors the formation of a vertical whirlwind having the effect of a waterspout. This whirlwind contributes toward the collection of the vapors to be evacuated and thus improves the purification of the area located above the working surface 2.

Depending on the extent of the entry section of the hood it obviously is possible to provide inside the hood several juxtaposed hoods, provided of course with their corresponding conduit.

The device as described can readily be constructed and may evidently be used for hoods of different shapes varying from that shown here.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. An evacuation device adapted for location in a room or the like for evacuating fumes or other gases from said room, said evacuating device comprising:

a vent hood having side walls and two ends; said hood being supported above the source of said fumes and having one of said hood ends disposed above and spaced from the source of fumes;

a fume conduit having two ends, one of said conduit ends disposed within said vent hood and spaced from said hood side walls and above said one hood end;

said conduit being partially disposed within said vent hood and extending outwardly from and substantially beyond said one hood end in the direction of said fumes;

said remaining conduit end being in close proximity to the fume source whereby it serves as a fume entrance port;

a fume deflector member located intermediate and connecting said vent hood and conduit;

said member having a small base portion forming a junction with said one conduit end disposed within said hood;

said member having side walls extending downwardly and outwardly from said junction and terminating in 4 a peripheral edge bearing against said hood side Walls at a point near said one hood end; and, said fume deflecting member side walls each having at least one groove located along said peripheral edge to provide a fume trap in the vicinity of said grooves to catch fumes which fail to pass into said fume entrance port in said conduit. 2. The improvement of claim 1, wherein said fume deflector member comprises a frusto-pyramidal shape.

3. The improvement of claim 2, wherein said grooves are rectangularly shaped and are located substantially in the center of the side walls of said fume deflector memher.

4. The improvement of claim 1, including suction means at the other end of said hood for urging said fumes into said fume conduit.

References Cited UNITED STATES PATENTS 1,671,524 5/1928 Gerdes 98-115 FOREIGN PATENTS 219,335 2/1910 Germany.

FRED C. MATTERN, ]R., Primary Examiner.

MANUEL ANTONAKAS, Assistant Examiner.

US. Cl. X.R. 

